Instruction Attribute Encoding for Opcode Map Storage
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Solution Overview
Problem
Extending an instruction set architecture while minimizing hardware complexity and opcode map expansion is challenging due to constraints in instruction encoding and storage.
Innovation Solution
Implementing a unique instruction attribute encoding method that maps, compresses, or replaces existing instruction fields with attribute fields, enabling compact instruction formats and additional features like extra source operands and increased data sizes for instructions, such as SIMD instructions, without significantly increasing storage requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional instruction encoding methods are used to extend the instruction set, then new instruction features can be added, but the opcode map size and storage requirements significantly increase
Solution Approach 1:
The patent segments the traditional monolithic opcode map into multiple smaller, organized tables including a primary opcode table, extension opcode tables, and attribute tables. This segmentation allows the system to store instruction information in a distributed manner across multiple smaller data structures rather than requiring one large opcode map, thereby reducing the peak storage requirement while maintaining comprehensive instruction set coverage.
Solution Approach 2:
The patent introduces a new dimension to instruction encoding by adding attribute fields that provide additional instruction information without expanding the traditional opcode space. This dimensional extension allows new instruction features to be encoded through attribute combinations rather than requiring new opcode entries, effectively adding capacity without increasing the base storage structure.
2Adaptability or versatility
If new instruction features are added to extend the instruction set, then processor functionality is enhanced, but hardware complexity increases
Solution Approach 1:
The patent creates a universal attribute encoding system that can represent multiple instruction features and extensions through a unified set of attribute fields and tables. This universal structure allows the same hardware decoding logic to handle both traditional instructions and new extended instructions, eliminating the need for separate hardware paths for different instruction types and thereby maintaining hardware simplicity while achieving instruction set extension.
Solution Approach 2:
The patent introduces attribute tables and extension opcode tables as intermediary data structures that mediate between the instruction stream and the execution logic. These intermediaries provide a layer of abstraction that translates diverse extended instructions into a unified internal representation, allowing the core hardware to remain simple while supporting complex instruction set extensions through software-configurable attribute definitions.
3Adaptability or versatility
If instruction fields are expanded to include more features, then new instruction types can be supported, but code size increases
Solution Approach 1:
The patent merges multiple traditional instruction fields into a unified attribute field structure where a single attribute can encode information that previously required multiple separate fields. This consolidation allows the system to represent complex instruction features using fewer bytes per instruction, reducing overall code size while maintaining the ability to express diverse instruction types through attribute combinations.
Data Source
AI summary
A technique for decoding an instruction in a variable-length instruction set. In one embodiment, an instruction encoding is described, in which legacy, present, and future instruction set extensions are supported, and increased functionality is provided, without expanding the code size and, in some cases, reducing the code size.